for player1 in 'cab':
    for player2 in 'xyz':
        if player1 == 'c' and player2 not in 'xz':
            remain2 = set('xyz') - set(player2)
            print("{}----{}\n".format(player1,player2))
        if player1 == 'a' and player2 != 'x' and player2 in remain2:
            remain2 -= set(player2)
            print("{}----{}\n".format(player1,player2))
        if player1 == 'b' and player2 in remain2:
            print("{}----{}\n".format(player1,player2))